Process for recrystallizing diaminotrinitrobenzene

ABSTRACT

1. A PROCESS FOR EFFECTING THE RECYCSTALLIZATION OF DIAMINOTRINITROBENZENE COMPRISING THE STEPS OF DISSOLVING DIAMINOTRINITROBENZENE IN DIMETHYL SULFOXIDE AT STEAM BATH TEMPERATURE, COOLING THE REACTION MIXTURE TO ABOUT 10*C. UNTIL PRECIPITATION IS ALMOST COMPLETE, FILTERING, WASHING THE PRECIPITATE WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF ETHANOL, METHANOL AND ACETONE TO DESTROY THE COMPLEX, AND DRYING AT ROOM TEMPERATURE.

United States atent O 3,715,398 PRUCESS FOR RECRYS'IALLIZHNG DHAMINOTRI- NITROBENZENE Martin H. Kaufman, China Lake, Calif assignor to the United States of America as represented by the Secre' tary of the Navy No Drawing. Filed Oct. 20, 1960, Ser. No. 63,934 int. Cl. C07c 85/16 US. Cl. 260-582 3 Claims The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a process for pretreating diarninotrinitrobenzene to achieve high density pressings capable of withstanding very high temperatures.

Those concerned with the development of explosives have long recognized the need for explosives capable of withstanding higher and higher temperatures. It is known to the art that maximum detonation velocity (D*) for any given explosive Will occur at that explosives maximum density. That is to say, if an explosive powder is pressed to shape and the pressed powder has a density which is 95% of the highest density possible, then its detonation velocity will be less than a powder pressed whose measured density is 98% of the highest density possible. This value is called the percent of the theoretical maximum density. In an explosive composition it is desirable to not only use ingredients of high density, but to use ingredients which press to a high percent TMD (theoretical maximum density). One of the materials found to have promise in this direction is diaminotrinitrobenzene, hereinafter called DATB. This is an explosive which has high impact insensitivity and can withstand temperatures up to 285 C. The greatest difiiculty up to the present has been the inability to press DATB to high percent TMD. DATB may be pressed to high density if the material is made very fine (generally done by ball milling for long periods of time) or if pressure applied is greater than 20,000 psi The present invention attains a very high percent TMD for diaminotrinitrobenzene as a result of a new and simple process of recrystallization amenable to large scale production.

An object of this invention is to produce a material useful in high temperature plastic-bonded explosives.

Another object is to produce a pressed explosive having a high percent theoretical maximum density for use in the rocket propellant field.

A further object of this invention is to provide a process amenable to large scale production for recrystallization of an explosive which permits close control of crystal size and density.

Other objects of this invention will be apparent from the following disclosure.

In the present process it was found that DATB dissolved in hot dimethyl sulfoxide and then cooled quickly to about 5-l0 C. produces a crystalline complex of dimethyl 3,715,398 Patented Feb. 6, 1973 sulfoxide and diaminotrinitrobenzene. This complex when filtered, may be washed with a polar solvent, such as, ethanol, methanol, or acetone and dried at room temperature. One-time recrystallized DATB can be pressed to greater than 96% theoretical maximum density. If DATB is twice recrystallized from dimethyl sulfoxide, the material is greatly improved and presses to better than 98% TMD.

In the present invention the DATB and hot dimethyl sulfoxide may be permitted to cool slowly to room temperature with slight agitation or stirring during the cooling down period until precipitation is complete. By this means larger crystals may be obtained than by the quick cooling procedure.

If two recrystallizations are desired, the first filtered DATB-dimethyl sulfoxide complex may be redissolved in fresh dimethyl sulfoxide, with the washings and dryings required only for the final recrystallization.

DATB may be recrystallized from several solvents other than dimethyl sulfoxide, for example, cyclohexanone, phenolics, dinitriles and ethylene carbonate, but generally high temperatures are required to get a reasonable quantity dissolved and an inert gas must be used to prevent excessive oxidation at these higher temperatures. The DATB purity appeared not to be greatly improved. Dimethyl sulfoxide is the best solvent found for DATB dissolving about 30% at steam bath temperature.

Various modifications are contemplated and may obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims.

What is claimed is:

1. A process for effecting the recrystallization of diaminotrinitrobenzene comprising the steps of dissolving diaminotrinitrobenzene in dimethyl sulfoxide at steam bath temperature, cooling the reaction mixture to about 10 C. until precipitation is almost complete, filtering, washing the precipitate with a solvent selected from the group consisting of ethanol, methanol and acetone to destroy the complex, and drying at room temperature.

2. A process for pretreating diaminotrinitrobenzene to achieve high density pressings capable of withstanding temperatures up to 285 C. comprising recrystallization of diaminotrinitrobenzene from dimethyl sulfoxide solution.

3. The process of claim 2 wherein the diaminotrinitrobenzene precipitate is redissolved in additional dimethyl sulfoxide at room temperature.

References Cited UNITED STATES PATENTS 3,072,662 1/1963 Murray, Jr. et al. 260-682 X.

LELAND A. SEBASTIAN, Primary Examiner U.S. Cl. X..R. 

1. A PROCESS FOR EFFECTING THE RECYCSTALLIZATION OF DIAMINOTRINITROBENZENE COMPRISING THE STEPS OF DISSOLVING DIAMINOTRINITROBENZENE IN DIMETHYL SULFOXIDE AT STEAM BATH TEMPERATURE, COOLING THE REACTION MIXTURE TO ABOUT 10*C. UNTIL PRECIPITATION IS ALMOST COMPLETE, FILTERING, WASHING THE PRECIPITATE WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF ETHANOL, METHANOL AND ACETONE TO DESTROY THE COMPLEX, AND DRYING AT ROOM TEMPERATURE. 